The effects of ionising radiation on implantable MOS electronic devices

dc.contributor.advisor Milthorpe, Bruce en_US Bradley, Peter en_US 2022-03-16T15:15:11Z 2022-03-16T15:15:11Z 1997 en_US
dc.description.abstract Space exploration and the rapid growth of the satellite communications industry has promoted substantial research into the effects of ionising radiation on modem electronic technology. The enabling electronics and computer processing has seen a commensurate growth in the use of radiation for diagnostic and therapeutic purposes in medicine. Numerous studies exist in both these fields but an analysis combining the fields of study to ascertain the effects of radiation on medically implantable electronics is lacking. A review of significant ground level radiation sources is presented with particular emphasis on the medical environment. Mechanisms of permanent and transient ionising radiation damage to Metal Oxide Semiconductors are summarised. Three significant sources of radiation are classified as having the ability to damage or alter the behavior of implantable electronics; Secondary neutron cosmic radiation, alpha particle radiation from the device packaging and therapeutic doses of high energy radiation. With respect to cosmic radiation, the most sensitive circuit structure within a typical microcomputer architecture is the Random Access Memory(RAM). A theoretical model which predicts the susceptibility of a RAM cell to single event upsets from secondary cosmic ray neutrons is presented. A previously unreported method for calculating the collection efficiency term in the upset model has been derived along with an extension of the model to enable estimation of multiple bit upset rates. An Implantable Cardioverter Defibrillator is used as a case example to demonstrate model applicability and test against clinical experience. The model correlates well with clinical experience and is consistent with the expected geographical variations of the secondary cosmic ray neutron flux. This is the first clinical data set obtained indicating the effects of cosmic radiation on implantable devices. Importantly, it may be used to predict the susceptibility of future implantable device designs to cosmic radiation. The model is also used as a basis for developing radiation hardened circuit techniques and system design. A review of methods to radiation harden electronics to single event upsets is used to recommend methods applicable to the low power/small area constraints of implantable systems. en_US
dc.language English
dc.language.iso EN en_US
dc.publisher UNSW, Sydney en_US
dc.rights CC BY-NC-ND 3.0 en_US
dc.rights.uri en_US
dc.source Thesis Digitisation Program en_US
dc.subject.other Random access memory en_US
dc.subject.other Metal oxide semiconductors en_US
dc.subject.other Implantable cardioverter-defibrillators en_US
dc.title The effects of ionising radiation on implantable MOS electronic devices en_US
dc.type Thesis en_US
dcterms.accessRights open access
dcterms.rightsHolder Bradley, Peter
dspace.entity.type Publication en_US
unsw.relation.faculty Engineering
unsw.relation.originalPublicationAffiliation Bradley, Peter, Graduate School of Biomedical Engineering, Faculty of Engineering, UNSW en_US
unsw.relation.originalPublicationAffiliation Milthorpe, Bruce , Graduate School of Biomedical Engineering, Faculty of Engineering, UNSW en_US School of Biomedical Engineering *
unsw.thesis.degreetype Masters Thesis en_US
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